Cycloparaffin production



us- 14, 1945. w. E. Ross ET AL 2,382,446 n CYCLOPARAFFIN PRODUCTION Filed June 21, 1944 lnvenl'ors: William E.Ross l Philip Pezz Patented Aug. 14, 1945 CYCLOPARAFFLN PRonc-'rioN William E. Ross, Berkeley, and Philip Peuaglia,

Cakiand, Calii'., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application June 21, 1944, Serial No. 541,445

15 Claims.` (Cl. 2260-666) This invention relates to-production of cycloparains of hydroaromaticstructure from hydrocarbon mixtures of relatively wide boiling range such as naphthenic gasolines or fractions thereof comprising cycloparaflins of hydroaromatic and non-hydroaromatic structure in admixture with open chain paraflin hydrocarbons. Theinvention relates more particularly to an improved process for the more eficient production of cyclohexane from naphthenic gasolines .and Afractions thereof comprising methylcyclopentane and cyclohexane.

The cycloparamns of hydroaromatic structure, particularly cyclohexane, are, of great value as starting materials and intermediates in the production of a wide variety of organic products. A most fertile source of these highly desirable materials resides in the naturally occurring hydrocarbon mixtures of naphthenic character such as naphthenic, natural and straight run gasolines. etc. Other sources comprise hydrocarbon mixtures of naphthenic character, boiling ln the gasoline boiling range, obtained by fractionation oi the products of many of the processes involving the catalytic or thermal treatment of hydrocarbons or carbonaceous materials. As iswell known; these readily available hydrocarbons constitute highly complex mixtures of a plurality of individual hydrocarbons, many of which have similar or closely approximating boiling points and many of which are capable of forming azeotropes with one another duringv distillation. Realization of the full advantages inherent in the many chemical processes relying upon the cycloparafns oi hydroaromatic structure as starting or intermediate materials has been handicapped by the lack of a process enabling emcient production of the cycloparailins of hydroaromatic structure on a practical scale from these' available complex mixtures. Not only is it imperative that such cycloparafdns of hydroaromatic structures be produced with high yields, but itl is essential that the product obtained beof a relatively high purity and yet involve the use of a -aration of either or both of these cycloparains from the complex hydrocarbon mixtures in Awhich they are generally-encountered .by such methods as fractional distillation,. if` at all possible, is

often rendered so involved and delicate an operation as to renderit highly'impractical. Resort'to such procedures as the initial separation of a fraction comprising both the methyicyclopentanes and cyclohexane, subjection of this fraction to isomerizing conditions effecting the conversion of methylcyclopentane to'cyclohexane, and fracl tionation of the isomeri'zate, has been found unsatisfactory. In addition to other difliculties, such a method generally does not enable the production of cyclohexaneof any substantial degree of purity. Thus, the isomerizate will contain hydrocarbons such as the open chain paraflin hydrocarbons having-seven carbon atoms to-the molecule including, for example, 2,2-dimethy1- pentane and 2,4-dimethylpentane, the boiling points of which are far too close to that of cyclohexane to enable separation by practical fractionating means. On the other hand, further separation of a Vinethylcyclopentane yconcentrate and' a higher boiling cyclohexane concentrate from this fraction, and subjection of the methylcyclopentane fraction separatelyto isomerizing conditions will result not only in the loss of methylcyclopentane in the cyclohexane concentrate, but still present the difculty of separatingl cyclohexane from admixture with C1 open chain paramns of close boiling point. lBy the term hydroaromatic cycloparamns, as used throughout this specification and appended claims is'meant the cycloparailins having a hexamethylene ring such as, for example, cyclohexane and the alkyl cyclohexanes, to distinguish them from cycloparafns of non-hydroaromatic structure comprising those having pentamethylene rings such as, for example, methylcyclopentane and other alkyl cyclopentanes.

It is an object of the present invention to provide` an improved'process for the more efficient structure in admixture with close boiling. open chain parailin hydrocarbons;

- Another object of the invention is the provision of an improved process for the more eiiicient production of ,cyclohexane from hydrocarbon the charge to the system.

mixtures of relatively wide boiling range auch as naphthenic gasolines. y

Still another object of the invention'is to provide an improved process for the more eilicient production -of cyclohexane from naphthenic gasoline fractions comprising methylcyclopentane. cyclohexane, and close boiling open chain paraillnic hydrocarbons.l Other objects and advantages of the invention will become apparent from the following description thereof.

In accordance with the process of the invention a hydrocarbon mixture of naphthenic character from any suitable source such as, for example, a naphthenic straight run gasoline is subjected to fractionation to separate a fraction comprising cycloparamns of non-hydroaromatic structure such as, for example, methylcyclopentane, and a fraction comprising cycloparanins of hydroaromatic structure such as, for example, cyclohexane. The fraction comprising cycloparatllns of non-hydroaromatic structure is subjected to isomerizing conditions in a first conversion zone to effect the conversion of cycloparains of non-hydroaromatic structure to cycloparaflins of hydroaromatic structure. The

fraction comprising cycloparafdns oi' hydroaromatic structure separated from the charge is subjected to isomerizing conditions in a second conversion zone to eiIect the conversion of cycloparaillns of hydroaromatic structure to cycloparaffins of non-hydroaromatic structure. Hydrocarbons comprising cycloparamns of non-hydroaromatic structure are separated from the eilluence of the second conversion zone-and passed to the inlet of the rst conversion zone. Edluence from the ilrst conversion zone is passed into a product separating zone to en'ect the separation therein of cycloparamns oi hydroaromatic structure in a high state of purity. As will be apparent from the following detailed description thereof, the invention enables not only a substantial increase in the total production of cycloparaffins of hydroaromatic structure from natural gasolines on a practical scale, but enables the obtaining of the desired product on a large scale in a greater state of purity.

In order to set forth more fully the nature of the invention it will be described herein in detail in its application to the production of cyclohexane from hydrocarbon mixtures of naphthenic character in the gasoline boiling range, with reference to vthe attached drawing in which the single figure represents a more or less diagrammatic elevational view of one form o f apparatus suitable for executing the process of the invention.

A hydrocarbon mixture of naphthenic character such as, for example, a napthenic straight run' gasoline is forced through valved line i into a feed fractionatorl 2. Within feed fractionator 2 a fraction comprising methylcyclopentane and cyclohexane is separated and forced through valved line 3 into a second fractionator 4. A- naphthenic gasoline. fraction. comprising methylcyclopentane and cyclohexane, from any source may be separately introduced through valved line l into line 3, and may comprise a part or all of The fraction passed into fractlonator 4 is of suiliicently wide boiling range to comprise substantially all of the methylcyclopentane and cyclohexane originally present in the straight run gasoline. A fraction boiling in the range of from about 65 C. to about 85 C. has been found particularly desirable. Such a fraction will unavoidably comprise a number of other hydrocarbons besides methylcyclopentane and cyclohexane, particularly normal hexane and straight and branched chain heptanes and some benzene. Within fractionator 4 the hydrocarbon fraction is further fractionated to separate a fraction comprising methylcyclopentane and a fraction comprising cyclohexane. The fraction comprising methylcyclopentane will generally boil in the range of from about 65 C. to about '15 C. and. will generally comprise some normal hexane and a small amount of benzene. The cyclohexane fraction will generally boil within the range of from about 75 C. to about 85 C. and will unavoidably comprise beside cyclohexane, dimethylpentanes and a small amount of methylcyclopentane. Although it is preferred to select as the fraction passed into fractionator 4 a fraction boiling in the range of from about 65 C. to about 85 C. a fraction of somewhat wider boiling range may suitably be used.- Under such conditions at least a part of the material lower boiling than methylcyclopentane preferably will be eliminated overhead from the fractionator 4, and hydrocarbons higher boiling. than cyclohexane will be eliminated as bottoms.

The methylcyclopentane fraction separated within fractionator 4 is forced through line 1 into a methylcyclopentane conversion zone 8. Within conversion zone 8 the methylcyclopentane fraction is contacted under cycloparanln isomerizing conditions with an isomerization catalyst. Suitable catalysts comprise those containing a metal halide of the Friedel-Crafts type, particularly those comprising a halide of aluminum, such as AlCh and/or AlBra. Particularly suitable catalysts comprise the organo-aluminum halide complexes, preferably a preformed aluminum chloride hydrocarbon complex. Other suitable catalysts comprise those of the molten salt type containing the aluminum halide in admixture with one or more other halide salts. 'I'he temperature in conversion zone 8 is maintained in the range of from about 20 C. to about 100 C. and preferably from about 50 C. to about 90 C. 'I'he particular temperature chosen within this specified temperature range will be governed to at least a substantial degree by the particular catalyst employed. When utilizing a preformed aluminum halide hydrocarbon complex as the catalyst a temperaturein the range of from about 65 C. to about 85 C. is somewhat preferred. A hydrogen halide promoter such as, for example, hydrogen chloride is introduced into the conversion zone by means of line Sn The hydrogen chloride is added in an amount equal to from about 0.1 to about 3% and preferably from about 0.5 to about 2% by weight of the hydrocarbon charge to the conversion zone. Higher or lower concentrations of the hydrogen chloride may at times be desirable depending upon variation in operating conditions. Under these conditions methylcyclopentane will be converted to cyclohexane in conversion zone 8.

Eiliuence from conversion zone 8 is passed through line Il into a stripping zone I2 wherein a vapor fraction comprising the hydrogen chloride promoter is separated and recycled to the conversion zone 8 by means of line 9. Make-up hydrogen chloride is introduced into the system by means of valved line I3. Liquid hydrocarbons are passed from the stripper I2 and forced through line I4 into a fractionator I5. Within fractionator l5 material lower boiling than cyclohexane and comprising unconverted methylcyclopentane is separated as a vapor fraction and re- A 30 minutes.

aseane cycled at least in part through lline Il to the conversion zone. The stream thus recycled may be subjected to fractionation to eifect separation of hydrocarbons other than methylcyclopentane therefrom prior to passage tothe conversion zone.

Liquid bottoms comprising cyciohexane andz In accordance with the process of tbeinyention the cyciohexane concentrate separated within fractionator 4 is passed through line 24 to cyciohexane conversion zone 2l. Within conversion zone 25 the hydrocarbons are contacted with kisomerization catalysts of the Friedel-Crafts type such as used in conversion zone 8. Temperature conditions maintainedin conversion zone 2l are;

and eliminated from the system as a final product through valved line 2 I.

,The etilciency with which methylcyclopentane in a straight run naphthenic gasoline fraction is converted to cyclohexane under theseconditions is illustrated by the following example.

Exmu I A straight run naphthenic gasoline was fractionated to separatetherefrom a methylcyclopentane-cyciohexane fraction boiling in the range of from 65 C. to 85 C. The composition of this fraction is given in Table I hi column A. This fraction was then subjected to further fractionation to separate therefrom a methylcyclopentane concentrate having a boiling range of from 65 C. to 75 C. and a cyciohexane concentrate having a boiling range of from 75 C. to 85 C. Thel composition of the methylcyclopentane and cyclohexane concentrates is given in `Table I in col umns B and C respectively. The methylcyclopent'ane concentrate was contacted with a preformed aluminum halide hydrocarbon complex at` a temperature of 80 C. and a contact time of HC1 in an amount equal to '1%' by weight of the charge was added to the conver- Vsion zone. A conversion of methylcyclopentane to cyciohexane of 75% was obtained. The composition of the isomerizate is given in column D of Table I. By further fractionation of they isomerizate a cyclohexane of a purity of 96% was obtained as indicated by thecomposition thereof shown in column E of Table I.

Table I Boiling range C 65-85 Composition per cent by volume:

Metbylpentanes n-Hsxsne Dimetbylpentanes. Methlcyclopentane Cyclo axane Benzene Undetermined...

@accom l Isomerizste. l Cyclohexanc product.

The cyciohexane of high purity thus produced represents the greater part yof the'methylcyclopentane content originally present in the feed. It

does, however, not comprise the cyclohexane orig inally present in the feed nor the smaller amount of methylcyclopentane unavoidabiy .comprised in the lcyciohexane Iconcentrate 'separated within fractionator I. The cyciohexane concentrate separated in fractionator l will unavoidably comprise. beside the cyciohexane. a substantial amount of open chain heptanes, certain isomers as cyciohexane of a purity of at least 95%.

however, maintained at a substantially higher vlevel than those within conversion zone'8. .'Ihus.

the temperature in conversion zone` 25 is maintained in the range'offrom about 110v C. to about tofsome extent with the type of catalyst used.

When utilizing a catalyst of the aluminum' halide hydrocarbon complex type, a temperature in the range of from about 140 C. to about 150 C. has been found particularly advantageous. A hydrogen halide promoter, for example, hydrogen chloride is introduced into the conversion zone by means of line 22. The hydrogen chloride is addedin an amount ranging from about 0.1 to about 3% and preferably from about 0.5 to about 2% of the hydrocarbon charge to the conversion zone. Somewhat higher or lower hydrogen chloride concentrations may, however, be employed.

Make-up hydrogen chloride is introduced into conversion zone 25 by means of line`29.

Under these conditions there is attained not only a conversion of cyciohexane to methylcyclopentane, which latter hydrocarbon is readily separable in relatively pure form by simple fractionating means from the isomerlzate, but there is effected a simultaneous conversion of dimethylpentanes to higher boiling materials. This has the very advantageous result of reducing the `amount; of dimethylpentanes admixed with the remaining unconverted cyciohexane in the isomerizate and enables the recycling of this mixture with ultimate substantially complete conversion of cyciohexane to methylcyclopentane.

Eiiluence from conversion zone 25 is passed through valved line 26't0 a stripping column 21.

Within stripping column 21 a vapor fraction comprising the hydrogen chloride promoter is separated and passed through line 28 to the conversion zone. Liquid hydrocarbons are passed Afrom the lower part of stripping column 2l through a valved line 30 into a product separating zone. The product separating zone is depicted in the drawing by means of the single fractionator 3l. In fractionator 3l material lighter boiling than methylcyclopentane is separated and eliminated through .valved line 32. The remaining isomerizate is separated therein into a relatively pure methylcyclopentane, a' cyciohexane lfraction and liquid bottoms comprising material higher boiling than cyciohexane. The cyclohexane fraction comprising some dimethylpentane not-separable therefrom'is taken from fractionator Il lthrough line 33 and recycled atleast in part to the 'conversion zone by means of line 34.

Relatively pure methylcyclopentane is taken from present in the straight run gasoline and not separable from parafiinic components thereof by fractionation is converted to methylcyclopentane and recovered as relatively pure methylcyclopentane suitable for conversion to cyciohexane of a high be converted therein to purity in the methylcyclopentane conversion zone of the system.

Exam-Lx II The cyclohexane concentrate boiling in the range of from 75 C. to 85 C. separated from the naphthenic gasoline charge in Example I, the

composition of which is given in column C of t Table I, was contacted with a preformed aluminum chloride hydrocarbon complex at a temperature of 140 C. and a contact time of 15 minutes. Hydrogen chloride in an amount of 0.5%

by weight of the hydrocarbon charge was added.

A conversion of cyclohexane to methylcyclopentane of 40% was'obtained. 'I'he composition of the isomerizate was as follows:

' Percent by volume Methylcyclopentane 33 Cyclohexane 47 Dimethylpentanes 'I Material higher boiling than cyclohexane 9 Material boiling below 65 C. 4

The isomerizate was fractionated to separate therefrom relatively pure methylcyclopentane for recycling to the methylcyclopentane conversion zone and a cyclohexane fraction for recycling tolysts. These catalysts may he used as such or in combination with suitable inert. solid diluent or support material. When utilizing isomerization catalysts of the heavy -metal sulilde type in conversion zone 25, temperatures in the range of from about 300 C. to about 600 C. and preferably from about 350 C. to about 400 C. are employed. lHydrogen is added to the charge in sumcient amount -to maintain a hydrogen pressure in the range of.

for example, from about 50 to about `200 atmospheres and higher. A line Il is provided for the introduction of hydrogen into the system. When thus operating, the conversion zone 25 at the hisher temperatures in the presence of hydrogen, stripping column 21 is replaced by suitable means for separating hydrogen from the isomerlzate..

Exlunnl III A cyclohexane concentrate boiling in the range of from 75 C. to 85- C. was separated by fractionation from a naphthenic straight run gasoline fraction. The cyclohexane concentrate had the following composition:

i Percent by volume l Dimethylpentanes 12 Methycyclopentane 7 Cyclohexane 'Z9 Benzene 1 Dimethylcyclopentane 1 The cyclohexane concentrate was passed over a molybdenum sulfide catalystat a temperature of 400 C. and a liquid hourly space velocity of .0.2.` Hydrogen was added to the charge to maintain a hydrogen pressure of approximately 860 pounds throughout the operation. Under these vconditions a '10% conversion of cyclohexane to methyl.

asaasse fractionated to separate relatively pure methylcyclopentane therefrom for passage to the l tion, over methods involving the isomerization of a single fraction comprising both methylcyclopentane and cyclohexane originally present in the charge.

' A Exsurr.: IV

A portion of the methylcyclopentane-cyclohexane fraction boiling in the range of from 65 C. to 85 C. separated from the napthenic gasoline charge in Example I, the composition of which is given in column A of Table I, was isomerized by contact with a preferred aluminum chloride hydrocarbon complex at a temperature of 80 C. with a contact time of 28 minutes. Hydrogen chloride in Ian amount equal to 1% by weight of the charge was added. The isomerizate had the following composition: v

. Percent Methyipentanes 13 Normal hexane 20 Dimethylpentane L 3 Methylcyclopentane 15 Cyclohexane 40 Benzene I 7 Higher boiling material. 2

The isomerizate was distilled to enect the separation of cyclohexane therefrom. The cyclohexane cut thus produced contained only 88% by volume of cyclohexane. The rest of the hexane cut consisted of benzene, 5%, and"dimethylpentane, 7%. Such a proportion of dimethylpentane is substantially above that tolerated'-` in many of the processeswherein cyclohexaneis utilized as starting or intermediate material. Reduction of the paraiilnic content of such a fraction on a large scale would be so costly as to render the process economically unfeasible. The process of the invention on the other hand, not only enables the recovery of substantially all of the available methylcyclopentane and cyclohexane in readily available naphthenic hydrocarbon mixtures, but enables their recovery as a cyclohexane of a purity of 95% or better.

Although the detailed illustrative description of the invention has been directed to the producldroaromatic structure having seven carbon atoms to the molecule, such' as, dimethylcyclopentane and a fraction comprising cycloparamns of hydroaromatic structure having seven carbon atoms to the molecule such as methylcyclohexane and y the parailinic hydrocarbons of close boiling range cyclopentane was attained. The isomerizate was inseparable therefrom by fractionation on a practical scale. The fraction comprising the cycloparafnn of hydroaromatic structure is passed to conversion sone 25 maintained at the higher temperature to effect the conversion of cycloparaffina of hydroaromatic structure to cycloparanins of non-hydroaromatic structure therein. The cycloparamns yof non-hydroaromatic structure are separated from the isomerizate, combined with the fraction comprising cycloparamns fof non-hydroaromatic structure separated yfrom the gasoline charge, and the combined streams passed into conversion zone 8 maintained at lower temperature. Within conversion zone 8 cycloparai'- ns of -non-hydroaromatic structure areV converted to cycloparaiiins of hydroaromatic lstructure, wh'ich areseparated asa iinal product froml the system.

-v vFor the purpose of simplicity parts of apparatus such as pumps, separators', coolers, condensers and detailed showing of reactors, catalyst separators,

accumulators, etc., not essential to complete and adequate description of the yinvention have been f omitted from the drawing. Similarly, fractionating zones depicted in the drawing by thesingle fractionators 2. 4 and 3| will, in actual practice, comprise the use of more than one fractionator to efiectfthe indicated separations.

We claim as our invention:

1. The process for the production of cyclohexi ane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain parailinshaving six and seven carbon atoms to the molecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a higher boiling fraction comprising cyclohexane and openchain paraffins having seven carbon atoms to the molecule from said hydrocar-bon mixture, contacting said higher boiling fraction with an aluminum chloride isomerization catalyst at cyclohexane isomerizlng conditions in the eluence of said methylcyclopentane conversion zone.

2. The process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain paramns having six and seven'carbon atoms to tl'e molecule, which'comprises separating a lower boiling fraction comprising Umethylcyclopentane and a higher boiling fraction comprising cyclohexane and open chain paraillns having seven carbon atomsI to the molecule from said hydrocarbon mixture, contacting said higher boiling fraction with an aluminum chloride isomerizationcatalyst at atemperature of from about 130 C. to-about 170 C. in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane'from the eilluence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lower boiling hydrocarbon fraction with an aluminum chloride isomerization catalyst at a temperature of from about 50C-to about 90 C. in

a methylcyclopentane conversion zone thereby,

convertingmethylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eilluence oi said methylcyclopentane conversion zone.

3. 'Ihe process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain paraillns having six and 'seven carbon atoms to the molecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a. higher boilingfraction comprising cyclohexane and open chain paraflins having seven carbon atoms to the molecule from said h'ydrocarbon mixture, contacting said higher boiling fraction with 'an -aluminum -halide isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane toA methylcyclopentane, separating hydrocarbons Ycomprising methylcyclopentane from the' eflluence of said cyclohexane conversion zone, contacting -said hydrocarbons comprising methylcyclopentane in adm'ixtu're with' said lower boiling hydrocarbon fraction with an aluminum halide isomerization catalyst at methylcyclopentane isomerlzing conditions in a methylcyclopen- -tane conversion zone thereby converting methylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eilluence of said methylcyclopentane conversion zone. 4. 'Ihe process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain parafllns having six and seven carbon atoms to the molecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a higher boiling fraction comprising cyclohexane and open chain paramns having seven carbon atoms to the molecule from said hydrocarbon mixture, contacting said high'er boiling fraction with an aluminum halide isomerization catalyst at a temperature 4of from about 110 C. to about 200 C. in a cyclohexane 'conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the eilluence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lower boiling hydrocarbon fraction with an aluminum halide isomerization catalyst at a temperature of from about 20 C. to about 100 C. in a methylcyclopentane conversion zone thereby converting methylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eilluence of said 'methylcyclopentane conversion zone.

5. The process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain parafllns having six and seven carbon atoms to i themolecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a higher boiling fraction comprising cyclohexane and open chain paramns having s ven carbon 'atoms to the molecule from said hy rocarbon mixture, contacting said higher boiling fraction with an isomerization catalyst comprising a metal halide of the Friedel-Crafts type at cyclohexane isonierizingf conditionsin a cyclohexane conversion zone thereby 'converting cyclohexane to n'iethylcyclopentane,` separating hy-A drocarbons comprising methylcyclopentane from the eilluence oi said cyclohexane conversion zone, contacting said hydrocarbons comprising methv -ylcyclopentane in admixture with said lower boiling hydrocarbon fraction with an isomerization catalyst comprising a metal halide of the Friedel-Crafts type at methylcyclopentane isomerizing conditions in a methylcyclopentane conversion zone thereby converting methylcyclopentane to cyclohexane. and separating hydrocarbons comprising cyclohexane from the emuence of `said methylcyclopentane conversion zone.

6. The process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain paramns having six and seven carbon atoms to the molecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a higher boiling fraction comprising cyclohexane and open chain paraiiins having seven carbon atoms to the molecule from said hydrocarbon mixture, contacting said higher boiling fraction with a molybdenum suliide isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the eilluence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lower boiling hydrocarbon fraction with an aluminum chloride isomerization catalyst at methylcyclopentane isomerizing conditions in a' methylcyclopentane conversion zone thereby converting methylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eiiluence o1'v said methylcyclopentane conversion zone.

7. The process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain paramns having six and seven carbon atoms to the molecule, which comprises separating a lower boiling fraction comprising methylcyclopentane and a higher boiling fraction comprising cyclohexane and open ch'ain parafnns having seven carbon atoms to the molecule from said hydrocarbon mixture, contacting said higher boiling fraction with a heavy metal sulfide isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the eilluence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lower boiling hydrocarbon fraction with an aluminum halide isomerization catalyst at methylcyclopentane isomerizing conditions in a methylcyclopentane conversion zone thereby converting methylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eilluence of said methylcyclopentane conversion zone.

8. 'I'he process for the production of cyclohexane from a hydrocarbon mixture comprising methylcyclopentane, cyclohexane and open chain paranins having six and seven carbon atoms to the molecule, which comprises separating a lowerl boiling fraction comprising methylcyclopentane and a. higher boiling fraction comprising cyclohexane and open chain paramns having seven carbon atoms to the molecule from said hydrocarbon mixture` contacting said higher boiling' fraction with an isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the emu'ence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with 'said lower boiling hydrocarbon fraction with an isomerization catalyst at methylcyclopentane isomerizing conditions in a methylcyclopentane conversion zone thereby converting methylcyclopentane to cyclohexane, and separating hydrocarbons comprising cyclohexane from the eiliuence of said methylcyclopentane conversion zone.

9. The process for the production of cyclohexane from naphthenic gasoline which comprises, separating a lower boiling fraction comprising methylcyclopentane having a maximum boiling point oi about '75 C. and a higher boiling fraction comprising cyclohexane having a maximum boiling point of Vabout 85 C. from said gasoline, contacting said higher boiling fraction with an aluminum halide isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the eiliuence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lowerl boiling fraction with an aluminum halide-isomerization catalyst at methylcyclopentane isomerizing conditions in a methylcyclopentane conversion zone thereby convert- Y line, contacting said higher boiling fraction withv an isomerization catalyst comprising a metal halide oi the Friedel-Crafts type at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby 4converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the etliuence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane in admixture with said lower boiling fraction with an isomerization catalyst comprising a metal halide of the Friedel-Crafts type at methylcyclopentane isomerizing conditions in a methylcyclopentane .conversion zone, thereby `converting methylcyclopentane to cyclohexane, and separating cyclohexane from the eiuence of said methylcyclopentane conversion zone.

11. The process for the production of cyclohexane from naphthenic gasoline which comprises, separating a lower boiling fraction comprising methylcyclopentane having a maximum boiling point of about '75 C. and a higher boiling fraction comprising cyclohexane having a maximum boiling point o! about C. from said gasoline, contacting said higher boiling fraction with a molybdenum suliide isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the etlluence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methylcyclopentane iny admixture with said lower boiling fraction with an aluminum halide-isomerization catalyst at methylcyclopentane isomerizing conditions in a methylcyclopentane conversion zone, thereby converting methylcyclopentane to cyclohexane, and separating cyclohexane from the eiiiuence of said methylcyclopentane conversion zone.

12. The process for the production ot cyclodroaromatic structure, which comprises separathexane from'. naphthenic gasoline which comprises, separating a lower boiling fraction comprising methylcyclopentane having a maximum boiling point of about '15 C. and a higher boiling fraction comprising cyclohexane having a maximum boiling point of about 85 C. from said gasoline, contacting said higher boiling fraction with an isomerization catalyst at cyclohexane isomerizing conditions in a cyclohexane conversion zone thereby converting cyclohexane to methylcyclopentane, separating hydrocarbons comprising methylcyclopentane from the elliuence of said cyclohexane conversion zone, contacting said hydrocarbons comprising methyicyclopentane in admixture with said lower boiling fraction with an `isomerization catalyst at methylcyclopentane isomerizing conditions in 'a methylcyclopentane conversion zone, thereby converting methylcyclopentane to cyclohexane, and separating cyclohexane from the eiiluence of said methylcyclopentane conversion zone.

13. The process for the production of cycloparafns of hydroaromatic structure from hydrocarbon mixtures comprising cycloparaflins of hydroaromatic and non-hydroaromatic structure and hydrocarbons diillcult to separate by fractionating means from said cycloparaflins of hydroaromatic structure, which comprises separating a fraction comprising cycloparafilns of nonhydroarornatic structure and a fraction comprising cycloparaiilns of hydroaromatic structure in admixture with hydrocarbons dliilcultly separable therefrom by fractionation from said mixture,

contacting said fraction comprising hydrocarbonsv of hydroaromatic structure with an aluminum halide isomerization catalyst at cycloparafin isomerizing conditions, thereby eil'ecting the conversion of cycloparaillns of hydroaromatic structure to cycloparafiins of non-hydroaromatic structure, separating hydrocarbons comprising said cyclovparaillns of non-hydroaromatic structure from the resulting isomerization products, contacting said cycloparaflins of non-hydroaromatic structure so produced in admixture with said fraction paraflins of hydroaromatic structure from hydrocarbon mixtures comprising cycloparamns of hydroaromatic and non-hydroaromatic structure v and hydrocarbons dilcult to separate by fractionating means from said cycloparamns of hying a fraction comprising cycloparains of 'nonhydroaromatic structure and a fraction comprising cycloparafiins of hydroaromatic structure in admixture with hydrocarbons dilcultly separable therefrom by fractionation from said mixture. contacting said fraction comprising hydrocarbons of hydroaromatic structure with a heavy metal sulfide` isomerization catalyst at cycloparan isopmerizing conditions, thereby eirecting the conversion of cycloparaillns of hydroaromatic structure to c ycloparailins of non-hydroaromatic structure,

. separating hydrocarbons comprising said cycloparaflins of non-hydroaromatic structure from the resulting isomerization products, contacting said cycloparafns of non-hydroaromatic structure so produced in admixture with said fraction comprising cycloparafflns of non-hydroaromatic structure separated from the charge with an isomerization catalyst comprising a metal halide of the Friedel-Crafts type at cycloparafiin isomerizing conditions, thereby converting cycloparafiins of non-hydroaromatic structure to cycloparafiins of hydroaromatic structure, and separating cycloparaillns of hydroaromatic structure from the resulting isomerization products.

15. The process for the production of cycloparalns of hydroaromatic structure from hydrocarbon mixtures comprising cycloparaiiins of hydroaromatic and non-hydroaromatic structure and hydrocarbons difilcult to separate by fractionating means from said cycloparaillns of :hydroaromatic structure, which comprises separating' a fraction comprising cycloparafflns of nonhydroaromatic structure and a fraction comprising cycloparaflins of hydroaromatic ,structure in admixture with hydrocarbons dilcultly separable therefrom by fractionation from said mixture,

contacting said fraction comprising hydrocarbons` of hydroaromatic structure with an isomerization catalyst at cycloparaiiin isomerizing conditions, thereby effecting the conversion of cycloparailins of hydroaromatic structure to cycloparaiilns of non-hydroaromatic structure, separating hydrocarbons comprising said cycloparalns of nonhydroaromatic structure from the resulting isomerization products, contacting said cycloparailins of non-hydroaromatic structure so produced in admixture with said fraction comprising cycloparafilns of non-hydroaromatic structure separated from the charge with an isomerization catalyst at cycloparaflinisomerizing conditions, thereby converting cycloparalns of non-hydroaromatic structure to cycloparaiiins of hydroaromatic structure, and separating cycloparafilns of hydroaromatic structure from the resulting isomerization products.

WILLIAM E. ROSS. PHILIP PEZZAGLIA. 

